i8i BOTANICAL GAZETTE. 



The inner surface of the perianth-cup has numerous fllat-heaess- 

 trichomes (PI. I, F), which have the cells of the short stalk comf)rded 

 ed vertically hke circular plates, and the four or six slighdy inflated 

 cells, which at first compose the head, often changed i ito a head of 

 many cells by formation of vertical, radial partitions. In the closely 

 related Sicyos, these flat-headed trichomes are so densely pressed to- 

 gether over the bottom of the cup, that in a cross section it appears at 

 first sight to have a second undulating epidermis supported on short 

 pillars. 



Each one of the prickles of the young ovary is tipped with a soli- 

 tary trichome (PI. I. E), like the capitate ones of young shoots, but 

 much larger, so large in fact that they can he discerned by the unas- 

 sisted eye. These disappear soon after fertilization, while the prick- 

 les continue to grow. The calyx-teeth and the lobes of the very young 

 leaves, which have the same histological structure and appearance as 

 the prickles on the ovary, ai e not thus equipped. 



There are scattered some trichomes of peculiar form among the 

 sort next mentioned. They consist of one comparatively large cell 

 with reticulated thickenings (PI. I, D), tipped with a small pear shap 

 ed cell. They are straight and rigid but rarely stand upright owing to 

 a weak base. 



All the free surface of the connectives, i. e. the surface of the 

 anthers not occupied by the thecae, boch at the apex and sides has the 

 epidermal cells produced into incipient trichomes (PI. I, A). Their 

 origin and form, and the fact that they are not united laterally, entitle 

 them to this classification. The slight cuticularization of their apices, 

 and total absence of ordinary epidermal cells indicate their near alli- 

 ance with true epidermis. 



A still more curious transitional form is presented in the epider- 

 mal tissue of the upper surface of the cotyledonary petioles (PI. I, H). 

 The epidermis, which is underlaid with a hypoderma of firm collen- 

 chyma, presents the anomaly of not being cuticularized. Its cell- 

 walls continue an unequal growth and meeting no outward resistance 

 expand their free surfaces piloseiy. The longer cells divide and be- 

 come several celled filiform trichomes. In Cucurbita the cotyledon 

 ary petioles, h;iving the usual cuticularized epidermis, are extremely 

 short, and entirely distinct from each other; Echin cystis has the pet- 

 ioles longer and slightly connate ; while Megarrhiza has very long pet- 

 ioles which are connate throughout, farming a tube. It seems quite 

 reasonable to presume that the upper (inner) surfaces of the cotyled- 

 onary petioles of Aiegarr/iiza will be found upon examination to be 

 still more strongly pilose by transformation of the epidermis, than those 

 of Echin'Kystis, because of the more perfect protection from environ- 

 mental influences. 



The last example shows a natural transition to trichome-like out 

 growths arising from a surface without epidermis. Such were found 

 (PI. I. C) projectinii into the central cavity of the hypocotyledonary 

 stem of an old plant. The wind had twisted the stem so as to rupture 

 it and expose the in.side to the weather. Some of the cells of the in 



